Tape data storage systems continue to be the systems of choice for backing up large amount of persistent data in enterprise data centers due to their relatively low cost. Examples of common tape drive systems include the IBM System Storage TS1130 Tape Drive products offered by International Business Machines corporation of Armonk, N.Y.
A tape drive system typically records data onto a magnetic tape medium enclosed in a tape cartridge and later retrieves the recorded data using a magnetic sensor commonly referred to as a magnetic tape head. In writing data files to a magnetic tape medium, a tape drive system periodically performs data synchronizations to ensure that related data in a hardware cache is written to the medium. A data synchronization may result from a “Write Tape Mark” channel command or writing a tape mark that separates two data files (or groups of data blocks) in a sequence.
Data synchronization can have a significant impact on tape drive performance. After a data synchronization has occurred, tape drive movement comes to a halt. When more data needs to be written to the medium, the drive must regain servo track acquisition. This typically involves some backward motion which gives the drive sufficient time and distance to achieve recording speed. This backward motion and reacquisition of servo tracks can take up a significant amount of time relative to the normal recording data rate. The impact of the data synchronization increases inversely with the size of the files being written. That is, with small files, there are more tape marks written relative to the actual data being written.
In addition to performance impact, it is difficult to determine a data recovery point when multiple files are embedded in a single physical tape file and data synchronization fails while the files are being written to a tape medium from the cache.
It is desirable to have a utility for controlling data synchronization events and determining affected files in synchronization failure in a tape storage system.